A Heian-era Japanese Shingon monk, one of the nittō hakke (入唐八家) Tang-pilgrim Japanese monks. Japanese name Eun 惠運. Born 798 CE; died 869 CE.
He traveled to Tang China in 842 and returned to Japan in 847 with Ennin’s 圓仁 embassy. His Tang stay coincided with the Huìchāng 會昌 persecution of 845 — making his Tang experience particularly traumatic and his successful return one of the more dramatic nittō hakke episodes. He produced two importation catalogs: KR6s0114 (general teaching-Dharma catalog) and KR6s0115 (vinaya-specific catalog).
After his return, he became a senior figure in the Heian Shingon-school institutional establishment, contributing to the post-Kūkai consolidation of Shingon at the imperial court.
Source: KR6s0114–KR6s0115; standard Japanese Heian Shingon-school sources.